diff mbox series

[7/7] KVM: SVM: hyper-v: Direct Virtual Flush support

Message ID aa634c867aa395aa2d3eae950dfec137f59a62c6.1617804573.git.viremana@linux.microsoft.com (mailing list archive)
State New
Headers show
Series Hyper-V nested virt enlightenments for SVM | expand

Commit Message

Vineeth Pillai April 7, 2021, 2:41 p.m. UTC
From Hyper-V TLFS:
 "The hypervisor exposes hypercalls (HvFlushVirtualAddressSpace,
  HvFlushVirtualAddressSpaceEx, HvFlushVirtualAddressList, and
  HvFlushVirtualAddressListEx) that allow operating systems to more
  efficiently manage the virtual TLB. The L1 hypervisor can choose to
  allow its guest to use those hypercalls and delegate the responsibility
  to handle them to the L0 hypervisor. This requires the use of a
  partition assist page."

Add the Direct Virtual Flush support for SVM.

Related VMX changes:
commit 6f6a657c9998 ("KVM/Hyper-V/VMX: Add direct tlb flush support")

Signed-off-by: Vineeth Pillai <viremana@linux.microsoft.com>
---
 arch/x86/kvm/svm/svm.c | 48 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)

Comments

Vitaly Kuznetsov April 8, 2021, 11:25 a.m. UTC | #1
Vineeth Pillai <viremana@linux.microsoft.com> writes:

> From Hyper-V TLFS:
>  "The hypervisor exposes hypercalls (HvFlushVirtualAddressSpace,
>   HvFlushVirtualAddressSpaceEx, HvFlushVirtualAddressList, and
>   HvFlushVirtualAddressListEx) that allow operating systems to more
>   efficiently manage the virtual TLB. The L1 hypervisor can choose to
>   allow its guest to use those hypercalls and delegate the responsibility
>   to handle them to the L0 hypervisor. This requires the use of a
>   partition assist page."
>
> Add the Direct Virtual Flush support for SVM.
>
> Related VMX changes:
> commit 6f6a657c9998 ("KVM/Hyper-V/VMX: Add direct tlb flush support")
>
> Signed-off-by: Vineeth Pillai <viremana@linux.microsoft.com>
> ---
>  arch/x86/kvm/svm/svm.c | 48 ++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 48 insertions(+)
>
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index 3562a247b7e8..c6d3f3a7c986 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -440,6 +440,32 @@ static void svm_init_osvw(struct kvm_vcpu *vcpu)
>  		vcpu->arch.osvw.status |= 1;
>  }
>  
> +#if IS_ENABLED(CONFIG_HYPERV)
> +static int hv_enable_direct_tlbflush(struct kvm_vcpu *vcpu)
> +{
> +	struct hv_enlightenments *hve;
> +	struct hv_partition_assist_pg **p_hv_pa_pg =
> +			&to_kvm_hv(vcpu->kvm)->hv_pa_pg;
> +
> +	if (!*p_hv_pa_pg)
> +		*p_hv_pa_pg = kzalloc(PAGE_SIZE, GFP_KERNEL);
> +
> +	if (!*p_hv_pa_pg)
> +		return -ENOMEM;
> +
> +	hve = (struct hv_enlightenments *)&to_svm(vcpu)->vmcb->hv_enlightenments;
> +
> +	hve->partition_assist_page = __pa(*p_hv_pa_pg);
> +	hve->hv_vm_id = (unsigned long)vcpu->kvm;
> +	if (!hve->hv_enlightenments_control.nested_flush_hypercall) {
> +		hve->hv_enlightenments_control.nested_flush_hypercall = 1;
> +		vmcb_mark_dirty(to_svm(vcpu)->vmcb, VMCB_HV_NESTED_ENLIGHTENMENTS);
> +	}
> +
> +	return 0;
> +}
> +#endif
> +
>  static int has_svm(void)
>  {
>  	const char *msg;
> @@ -1034,6 +1060,21 @@ static __init int svm_hardware_setup(void)
>  		svm_x86_ops.tlb_remote_flush_with_range =
>  				kvm_hv_remote_flush_tlb_with_range;
>  	}
> +
> +	if (ms_hyperv.nested_features & HV_X64_NESTED_DIRECT_FLUSH) {
> +		pr_info("kvm: Hyper-V Direct TLB Flush enabled\n");
> +		for_each_online_cpu(cpu) {
> +			struct hv_vp_assist_page *vp_ap =
> +				hv_get_vp_assist_page(cpu);
> +
> +			if (!vp_ap)
> +				continue;
> +
> +			vp_ap->nested_control.features.directhypercall = 1;
> +		}
> +		svm_x86_ops.enable_direct_tlbflush =
> +				hv_enable_direct_tlbflush;
> +	}
>  #endif
>  
>  	if (nrips) {
> @@ -3913,6 +3954,13 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu)
>  	}
>  	svm->vmcb->save.cr2 = vcpu->arch.cr2;
>  
> +#if IS_ENABLED(CONFIG_HYPERV)
> +	if (svm->vmcb->hv_enlightenments.hv_vp_id != to_hv_vcpu(vcpu)->vp_index) {

This looks wrong (see my previous comment about mixing KVM-on-Hyper-V
and Windows/Hyper-V-on-KVM). 'to_hv_vcpu(vcpu)->vp_index' is
'Windows/Hyper-V-on-KVM' thingy, it does not exist when we run without
any Hyper-V enlightenments exposed (e.g. when we run Linux as our
guest).

> +		svm->vmcb->hv_enlightenments.hv_vp_id = to_hv_vcpu(vcpu)->vp_index;
> +		vmcb_mark_dirty(svm->vmcb, VMCB_HV_NESTED_ENLIGHTENMENTS);
> +	}
> +#endif
> +
>  	/*
>  	 * Run with all-zero DR6 unless needed, so that we can get the exact cause
>  	 * of a #DB.
diff mbox series

Patch

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 3562a247b7e8..c6d3f3a7c986 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -440,6 +440,32 @@  static void svm_init_osvw(struct kvm_vcpu *vcpu)
 		vcpu->arch.osvw.status |= 1;
 }
 
+#if IS_ENABLED(CONFIG_HYPERV)
+static int hv_enable_direct_tlbflush(struct kvm_vcpu *vcpu)
+{
+	struct hv_enlightenments *hve;
+	struct hv_partition_assist_pg **p_hv_pa_pg =
+			&to_kvm_hv(vcpu->kvm)->hv_pa_pg;
+
+	if (!*p_hv_pa_pg)
+		*p_hv_pa_pg = kzalloc(PAGE_SIZE, GFP_KERNEL);
+
+	if (!*p_hv_pa_pg)
+		return -ENOMEM;
+
+	hve = (struct hv_enlightenments *)&to_svm(vcpu)->vmcb->hv_enlightenments;
+
+	hve->partition_assist_page = __pa(*p_hv_pa_pg);
+	hve->hv_vm_id = (unsigned long)vcpu->kvm;
+	if (!hve->hv_enlightenments_control.nested_flush_hypercall) {
+		hve->hv_enlightenments_control.nested_flush_hypercall = 1;
+		vmcb_mark_dirty(to_svm(vcpu)->vmcb, VMCB_HV_NESTED_ENLIGHTENMENTS);
+	}
+
+	return 0;
+}
+#endif
+
 static int has_svm(void)
 {
 	const char *msg;
@@ -1034,6 +1060,21 @@  static __init int svm_hardware_setup(void)
 		svm_x86_ops.tlb_remote_flush_with_range =
 				kvm_hv_remote_flush_tlb_with_range;
 	}
+
+	if (ms_hyperv.nested_features & HV_X64_NESTED_DIRECT_FLUSH) {
+		pr_info("kvm: Hyper-V Direct TLB Flush enabled\n");
+		for_each_online_cpu(cpu) {
+			struct hv_vp_assist_page *vp_ap =
+				hv_get_vp_assist_page(cpu);
+
+			if (!vp_ap)
+				continue;
+
+			vp_ap->nested_control.features.directhypercall = 1;
+		}
+		svm_x86_ops.enable_direct_tlbflush =
+				hv_enable_direct_tlbflush;
+	}
 #endif
 
 	if (nrips) {
@@ -3913,6 +3954,13 @@  static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu)
 	}
 	svm->vmcb->save.cr2 = vcpu->arch.cr2;
 
+#if IS_ENABLED(CONFIG_HYPERV)
+	if (svm->vmcb->hv_enlightenments.hv_vp_id != to_hv_vcpu(vcpu)->vp_index) {
+		svm->vmcb->hv_enlightenments.hv_vp_id = to_hv_vcpu(vcpu)->vp_index;
+		vmcb_mark_dirty(svm->vmcb, VMCB_HV_NESTED_ENLIGHTENMENTS);
+	}
+#endif
+
 	/*
 	 * Run with all-zero DR6 unless needed, so that we can get the exact cause
 	 * of a #DB.